The Power of Information

National Drinking Water Database


Storm Lake Water Treatment Plant Utilities - Storm Lake, IA


Serves 10,329 people

Total trihalomethanes (TTHMs)

Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.
 
This Drinking Water System
Test Days Exceeding Health GuidelinesDefinition of what this is
17 days
Test Days Exceeding Legal LimitsNumber of days in which the samples taken in that day exceed the Maximum Contaminant Level (Depending on the contaminant and its MCL, that may or may not trigger an MCL violation. Some MCLs are based on averages spanning several months to a year)
2 days
Test DaysNumber of days in which this chemical has reported results in the data we received from the State
23 days
Tests ConductedNumber of individual tests done for this contaminant
47 tests

Testing Summary

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.37.24 ppb
110 ppb
Yes
9.8 ppb
Yes
80 ppb
NOTE: Each dot in the above graph represents one month.
* Water utilities are noted as exceeding the legal limit if any test is above the maximum contaminant level (MCL). Most MCLs are based on annual averages so exceeding the MCL for one test does not necessarily indicate that the system is out of compliance.

Health Based and Legal Limits for Total trihalomethanes (TTHMs)

Health Based Limits for Total trihalomethanes (TTHMs)

StandardDescriptionLevel
One in one million (10-6) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 1,000,000. Source: U.S. Environmental Protection Agency.9.8 ppb
EPA Human Health Water Quality CriteriaWater quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.11.5 ppb
Maximum Contaminant Limit (MCL)The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.80 ppb
Lifetime health-based limit, non-cancer riskConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for a lifetime of exposure. The Lifetime health-based limit (or Health Advisory, HA) is based on exposure for a a 70-kg adult consuming 2 liters of water per day. Source: U.S. Environmental Protection Agency.130 ppb
One in ten thousand (10-4) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.980 ppb
Drinking Water Equivalent LevelA lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.1835 ppb
Children's health-based limit for 10-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic effects for up to ten days of exposure. The Ten-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.4860 ppb
Children's health-based limit for 1-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for up to one day of exposure. The One-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.10600 ppb

Testing Results

Testing DateAverage
Result
Samples taken that dayNumber of Non-DetectsRange of Results
2009-04-140 ppb110 ppb
2009-01-070 ppb770 ppb
2008-10-080.53 ppb760 to 3.7 ppb
2008-07-0828.86 ppb7015 to 58 ppb
2008-04-0826.43 ppb7011 to 50 ppb
2008-01-2867 ppb1067 ppb
2007-10-3064 ppb1064 ppb
2007-08-2151 ppb1051 ppb
2007-07-050 ppb110 ppb
2007-05-0145 ppb1045 ppb
2007-02-1359 ppb1059 ppb
2006-11-1458 ppb1058 ppb
2006-09-0669 ppb1069 ppb
2006-05-0845 ppb1045 ppb
2006-03-1437 ppb1037 ppb
2005-12-19110 ppb10110 ppb
2005-09-2690 ppb1090 ppb
2005-05-3142 ppb1042 ppb
2005-03-1516 ppb1016 ppb
2004-12-2827 ppb1027 ppb
2004-09-2216 ppb1016 ppb
2004-06-304.7 ppb104.7 ppb
2004-03-300 ppb110 ppb